SANAA, Yemen — Hours after Saudi Arabia declared an end to its coalition's nearly monthlong air campaign in Yemen, new airstrikes Wednesday hit Iran-backed militants and their allies in two cities, and the rebels said they would welcome U.N.-led peace talks in the conflict that has killed more than 900 people.

The continued airstrikes suggested that the U.S.-backed offensive, aimed at restoring Yemen's internationally recognized president, was entering a new phase in which the Saudi-led military action will be scaled back but not halted completely.

Air raids struck positions held by the rebels, known as Houthis, and their allies in the southern port of Aden and the central city of Taiz, Yemeni officials said. Fighting continued in both areas between the rebels and supporters of exiled President Abed Rabbo Mansour Hadi, a close U.S. ally who fled Yemen on March 25.

The capital of Sanaa was calm, however, giving residents their most peaceful night in almost four weeks. In the evening, thousands of pro-Houthi demonstrators marched and vowed they would never submit to what they described as "Saudi-American aggression."

The Shiite rebels are backed by former President Ali Abdullah Saleh, an autocrat who ruled the impoverished but strategic country for three decades until he was removed amid a 2011 Arab Spring uprising. His military forces have aided the rebels who advanced from the north and control much of Yemen, including Sanaa.

Saudi Arabia and a coalition of its Gulf allies began the air campaign March 26, aimed at crushing the Houthis and allied military units loyal to Saleh. The Saudis believe the rebels are tools for Iran to take control of Yemen. Iran has provided political and humanitarian support to the Houthis, but both Tehran and the rebels deny it has armed them.

The airstrikes in Taiz hit the rebels as they gathered at a military headquarters they control near the old airport southeast of the city, officials said. Also targeted was Aden, where warplanes blasted rebel forces in outlying districts.

Street fighting continued in both cities, especially Taiz, where officials said pro-government forces control most of the city, and dozens were killed on both sides. In Aden, rebels fired mortars, said the officials, who spoke on condition of anonymity because they were not authorized to talk to journalists.

At least 944 people were killed and 3,500 wounded since the coalition airstrikes began March 26, the World Health Organization said. It also has created an escalating humanitarian crisis, with dwindling supplies of food, water and medicine.

The rebels and their allies have lost little ground, and Hadi remains in exile in Saudi Arabia. Aden, where he had established a temporary capital before fleeing, is gripped by fierce fighting. Al-Qaida's powerful local affiliate has exploited the chaos to seize the southeastern port city of Mukalla.

On Tuesday, Saudi Arabia declared "Decisive Storm" over and announced the start of a more limited military campaign aimed at preventing the rebels from operating.

At a news conference in Riyadh, coalition spokesman Brig. Gen. Ahmed Asiri said the heavy airstrikes would be scaled down, but did not confirm whether they would stop altogether. He said the goals of the new operation are to prevent Houthi rebels from "targeting civilians or changing realities on the ground."

Riad Kahwaji, director of the Dubai-based Institute of Near East And Gulf Military Analysis, said that if there were any suspicious military movements, "the coalition will attack it."

In Washington, Saudi Ambassador Adel al-Jubeir said his country would continue responding to Houthi attacks despite the change in mission, and he suggested strikes coming within hours to head off a three-pronged attack by militants on Aden.

"We will not allow them to take Yemen by force," he said at a news conference.

Al-Jubeir criticized the Houthis for talking about mediation while persisting in attacks and expressed doubt they would adhere to any cease-fire or power-sharing deal after violating dozens of previous agreements.

U.N. Secretary-General Ban Ki-moon said he "took note" of Saudi Arabia's announcement and expressed concern at the renewed fighting. He welcomed the Saudi-led coalition's announcement it supports a quick resumption of the political process and the delivery of humanitarian aid.

Ban said he is waiting for "positive responses" from key parties to his choice for a new special envoy to Yemen — widely reported to be the current U.N. Ebola chief, Ismail Ould Cheikh Ahmed.

Houthi leaders were conciliatory in an official statement Wednesday, calling for a resumption of dialogue and any efforts under the auspices of the U.N. that lead to a peaceful compromise. It was a far cry from a defiant speech by rebel leader Abdul-Malek al-Houthi on Sunday, when he vowed to not surrender and rejected U.N. efforts.

"We welcome any United Nations efforts that are on the side of peaceful solutions," Houthi spokesman Mohamed Abdul-Salam said in the statement. The return to talks was a key demand of a Security Council resolution that calls on Yemenis, especially the Houthis, to end the violence and return to the U.N.-led talks.

Iran welcomed the Saudi decision to halt "Decisive Storm" and launch a new one called "Renewal of Hope."

"We believe this was a positive step," said Foreign Ministry spokeswoman Marzieh Afkham, adding that "political cooperation" by all parties was needed to resolve the Yemen crisis.

The U.S. also welcomed the conclusion of the Saudi-led operation, saying it looked forward to a shift from military operations to a quick resumption of negotiations.

"We strongly urge all Yemeni parties, in particular the Houthis and their supporters, to take this opportunity to return to these negotiations as part of the political dialogue," National Security Council spokeswoman Bernadette Meehan said. "The Yemeni people deserve the opportunity to hold a peaceful debate about their new constitution, to participate in a credible and safe constitutional referendum, and to vote in free and fair national elections."

In an apparent goodwill gesture Wednesday, the rebels released Defense Minister Mahmoud al-Subaihi, as well as Hadi's brother and a third military commander after holding them for nearly a month. Airport officials said a plane arrived in Sanaa to take al-Subaihi, Hadi's brother and two army commanders to Riyadh.

The move could reflect an imminent political deal between Hadi and the rebels and their allies.

Also on Wednesday, Yemen security officials said a likely U.S. drone strike killed seven suspected al-Qaida fighters in the eastern part of the country. They said the militants were traveling by car in Mukalla, the capital of Hadramawt province, where al-Qaida has recently made advances and struck deals with tribesmen.

The Interior Ministry said suspected al-Qaida gunmen on a motorcycle killed a security officer in a drive-by shooting.

The chaos in Yemen has forced the U.S. to scale back drone strikes on al-Qaida in the Arabian Peninsula, as the local affiliate is known. The group has carried out a number of failed attacks on the U.S. and claimed the deadly attack on the French satirical magazine Charlie Hebdo earlier this year.